Combustion Dynamics and Fuels—Series 4: the Dynamo Solution

Here at Dynamo we’ve taken a look at this problem of fuel flexibility, and built a power solution that is truly fuel agnostic.  While the product we are building requires a lot of engineering and years of experience (our technical advisory team spans 100+ years of combined turbine development experience), the solution itself has several key features that allow us to tackle this challenging technical problem.
The first thing we decided was to build a gas turbine engine, as they are renowned for their fuel flexibility.  In many ways a gas turbine is just a set of compressors and expanders set around a combustion tube.  As long as a combustion chamber can be made to reliably burn fuel, a turbine can be built around it.
We then developed a combustion chamber that can accommodate a wide range of BTU contents.  The challenge here was to ensure complete combustion and low pressure loss for a variety of fuel mixtures at both startup and steady-state operation.  The combustion chamber that we have developed has achieved all of this.

 

Although the combustion chamber is great, we do not rely on it 100% to ensure the reliability of our engine.  To that end we’ve included a specialized fuel conditioning system that is closely monitored by our supervisory control system.  The fuel conditioning system serves as a buffer between the wellhead and the combustion chamber, such that the fuel quality does not vary drastically over short periods of time and reduces the amount of work needed for the control system to regulate fuel flow.
Deploying our product in the oilfield adds additional complexity.  As discussed above, on the fuel supply side the consistency of the fuel can vary significantly over a few hours, and it is challenging to quantify that fuel a priori.  Additionally, on the demand side, pump jacks and other field equipment have a variety of duty cycles which change the amount of power required at any given moment.  To meet these needs, our solution has to be more than a combustion system.  It is tasked with the double duty of converting a variable energy of one type [fuel] while trying to meet varying output demands—all within very short time frames.  To enable smooth operations, this is achieved with several features, including a proprietary control system and a sophisticated custom power electronics package.
We can talk all day about how we do things, but our customers care about results.  In the lab to date we have verified the ability to operate on fuels ranging from 500-2045 BTU / scf in a single unit.  Across this range we were able to start the engine, bring it to power, and sustain operations as the fuel content was varied.  We were also able to do this with liquid water injected into the fuel lines—we were able to do this with a water cut of 80% by mass.  This effective range and the ability to handle liquids in the combustion system show that we can sustain combustion in virtually any oil field.   A more technical summary can be found in our whitepaper here.